Best you get an Astro Flight Watt-Meter & CHECK your setup for yourself!

Jim

npm:
As a former HS Physics teacher, I can confirm you are correct!

fixer:
The reason Chuck is interested in watts is that is really what matters in working with motors. In fact, it is really the energy lost to heat that matters, since that is what heats up the motor and too much heat will either demagnetize the permanent magnets or melt the insulation on the windings, shorting it out. Programs like MotoCalc come in handy when selecting the correct propeller since they can show the watts lost to heat. The programs get you close, but real world testing (via current and voltage meters or an integrated meter like the Astro Whattmeter) is necessary, particularly if you are using expensive and current sensitive lipo packs.

The motor manufacturers give the limits in interesting ways; they specify the voltage limit since that is proportional to the rpm and if the motor spins too fast it will throw a magnet damaging the motor; then they specify the current limit since the wire is a fixed diameter and if you try to run more current through the wire it will heat up and melt the insulation, and then assuming you are running less than the max voltage and max current, they tell you the max wattage because that is all the heat the motor can dissipate (you check your own current x voltage).

These are all just approximations anyway. Depending upon how much air flow you have over the motor, and the ambient air temperature, you can push the motor past the specs without any trouble. The Stryker flown on a 50F day is great with motor out in the open and lots of cold air flowing over it. Put the same motor inside a Tiger Moth 400 with a fully enclosed cowl and you will cook it.

Although becoming an avid pilot over the past few months, there are always the questions that humble me.

My concerns with WATTS are driven simply from a guy who does not know better; and after three decades of 'just trying it' and then leaving 'it' in a box after I screwed it up...I now ask the proverbial experts before I jump.
With age comes wisdom; and mine is the wisdom of inquiry...don't try to do plumbing, dont try to fix a microwave, and for the love of my mother...DONT HOOK UP A 4s LIPO to a 300 dollar power system and then toss it into the air if all you are going to do is make a flying ball of fiery styrofoam.

(hey, it only took 30 years, right?)

I still slip sometimes, though...like buying the wring gearbox for a mega motor...(see my post in 'power systems')

Thanks for being my mentaurs in this new hobby...and I will have MORE questions. I do have a MEDUSA power meter...bet have not assembled all of the equipment yet...motocalc says my setup is good....I just want a 'human' opinion before I jump.

fixer:
The reason Chuck is interested in watts is that is really what matters in working with motors.
FoamCrusher

I'll grant you that watts is a part of the entire equation, but overall has little value to us in these particular situations. Both mfg's of these brushless motors & LiPo's are primarily concerned with MAX amp draw. The brushless motor's rating include cell count based on 1.2volt NiCd/NiMh style batteries, for voltage limitations.
Nice to know the wattage information, but we only need concern ourselves with amps & volts.

My concerns with WATTS are driven simply from a guy who does not know better; and after three decades of 'just trying it' and then leaving 'it' in a box after I screwed it up...I now ask the proverbial experts before I jump.

(hey, it only took 30 years, right?)

Chuck

Hey, we're ALL still learning, if not you're dead.

I've been checking my F-27 Styker brushless/LiPo setup for flight enduance times. WOT for most of a flight & I get around 9 minutes. Conservative flying, some motor off/gliding, and I've gone 16 minutes.

...I put all my stuff together from LHS, Hobby-Lobby (motor), and Bishop Power Products (ESC)....

--C

AirCraft World in Japan - quick shipping (only $2.50 world wide) and no sales tax. I get items here on the left coast within 5 days.

When looking for the best deal, the added tax and shipping make a difference when the total of all of the items starts getting up there. I can usually get another item for what I save buying from Dave.

Bishop PP, eDogFight, and e-Flightline are my other favorite places, but the CA sales tax is a price killer for me on big purchases.

I just saw an ad in the for sale section here. Hobbys and beyond are running specials until the end of the year. I haven't dealt with them yet, but may place an order. "combo deal= Mega 16/15/4 and CC Phoenix 25 =$135.00 " They are offering free shipping too. Best price I've seen yet.
Tim

I just saw an ad in the for sale section here. Hobbys and beyond are running specials until the end of the year. I haven't dealt with them yet, but may place an order. "combo deal= Mega 16/15/4 and CC Phoenix 25 =$135.00 " They are offering free shipping too. Best price I've seen yet.
Tim